Algebra 2 Common Core

Published by Prentice Hall
ISBN 10: 0133186024
ISBN 13: 978-0-13318-602-4

Chapter 12 - Matrices - Mid-Chapter Quiz - Page 791: 11

Answer

$X = \begin{bmatrix} 14 & 6 \\ -12 & 8 \end{bmatrix}$

Work Step by Step

Using the properties of matrix equality, the given matrix equation, $ \begin{bmatrix} -3 & 2 \\ 5 & -1 \end{bmatrix} = \begin{bmatrix} 4 & 5 \\ -1 & 3 \end{bmatrix} -\dfrac{1}{2}X ,$ is equivalent to \begin{align*} \begin{bmatrix} -3 & 2 \\ 5 & -1 \end{bmatrix} - \begin{bmatrix} 4 & 5 \\ -1 & 3 \end{bmatrix} &= \begin{bmatrix} 4 & 5 \\ -1 & 3 \end{bmatrix} - \begin{bmatrix} 4 & 5 \\ -1 & 3 \end{bmatrix} -\dfrac{1}{2}X \\\\ \begin{bmatrix} -3-4 & 2-5 \\ 5-(-1) & -1-3 \end{bmatrix} &= -\dfrac{1}{2}X \\\\ \begin{bmatrix} -3-4 & 2-5 \\ 5+1 & -1-3 \end{bmatrix} &= -\dfrac{1}{2}X \\\\ \begin{bmatrix} -7 & -3 \\ 6 & -4 \end{bmatrix} &= -\dfrac{1}{2}X \\\\ -2\begin{bmatrix} -7 & -3 \\ 6 & -4 \end{bmatrix} &= \left(-\dfrac{1}{2}X\right)2 \\\\ \begin{bmatrix} -7(-2) & -3(-2) \\ 6(-2) & -4(-2) \end{bmatrix} &= \left(-\dfrac{1}{2}X\right)(-2) \\\\ \begin{bmatrix} 14 & 6 \\ -12 & 8 \end{bmatrix} &= X .\end{align*} Hence, $ X = \begin{bmatrix} 14 & 6 \\ -12 & 8 \end{bmatrix} .$
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